Working memory refers to the active mental retention of information, to its manipulation, and to its use in guiding behavior. Its role in many types of high level cognition, as a factor underlying individual differences across a broad spectrum of experimental and real world measures, and as a factor in many psychiatric and neurological diseases, makes it important to many branches of cognitive and clinical neuroscience. The focus of this proposal is to elucidate the contributions of neural oscillations to working memory and to the related cognitive construct of attention. Oscillations are ubiquitous in the brain, but their role in supporting many types of cognition and behavior remains poorly understood and, in some cases, controversial. The methodological approach is to measure neural oscillations during cognitive task performance with the electroencephalogram (EEG), in some cases while simultaneously applying repetitive transcranial magnetic stimulation (rTMS), and in some cases applying multivariate pattern classification analysis (MVPA) to the data. rTMS can extend what can be learned with EEG alone in many ways: It can bias endogenous, delay-period oscillations to demonstrate their causal influence on behavior; it can unmask functionally relevant components of the EEG that are not evident in EEG-only data; and it can provide direct indices of effective connectivity. MVPA is an important tool for this research, because it can assess whether a signal is representing the information that is being held in working memory (something that cannot be inferred by more tradition techniques that rely on interpretation of signal intensity levels). Two specific aims are addressed in this proposal. The first is to test th hypothesis that delay-period oscillatory activity carries stimulus-specific information. Two foci o this aim will be the neural mechanism for storing information that is in working memory, but outside the focus of attention, and addressing whether an event-related potential associated with working memory, contralateral delay activity (CDA), reflects information storage per se, or a more general state that is sensitive to cognitive load. The second specific aim is to test the hypothesis that working memory and attentional tasks are supported by common oscillatory patterns, and that the functions of these patterns vary with context. These studies will contribute to theoretical models of working memory, as well as to a better understanding of the mechanistic role of neuronal oscillations in working memory and attention. In addition to the basic science questions outlined here, there is translational relevance for this work for the diagnosis and treatment of psychiatric disorders that are associated with abnormal neural oscillations.